Process of manufacture of pulp and paper



Patented July 7, 1931 T STATES PATENT QFFICE I LEVIS MILLER BOOTH, F PLAINFIELD, NEW JERSEY PROCESS 0]! MANUFACTURE OF PULP AND PAPER No Drawing.

& ing with or reducing the usual washing process and treating the pulp with chlorine.

In the process of manufacturing paper or paper board, as for example kraft or straw paper or board, the wood chips or straw have heretofore been treated by an alkaline process for the purpose of loosening the lignins, resins and other non-fibrous substances from the fi brous material. The former were then separated from the latter by a washing process which results in the production-of voluminous quantities of alkaline wash water carrying non-fibrous organic matter as well as an appreciable amount of fibrous material. By processes heretofore practiced the alkaline wash water. together with its burden of mineral and organic matter is either wasted, or treated by recovery or disposal processes.

I have found that it is possible to increase the yield of paper or board and at the same time to eliminate washing entirely or to materially lessen the volume of wash water required by terminating the pulp washing process at a time when an appreciable amount of alkali still persists which. if left free in the pulp. is detrimental in the subsequent paper or board making processes and the product.

After digesting the pulp by an alkaline process I introduce chlorine into the stock either directly as a gas or as a water solution or as a chlorine compound from which chlorine is released and thereby neutralize the residue of alkali remaining after the digestion or cooking process. One example of the application of my process which I have found to be practicable is as follows For the manufacture of straw paper or board, straw is cooked in the presence of an alkali. The pulp is then washed for the purpose of removing the excess alkali and nonfibrous material. In my improved process I- dispense with washingentirely' orgliscon;-

'- tinuethe washing after a fraction of the usual washing period. I subsequently add the chlorine. This treatment causes a neutralization Application filed October 5, 1928. Serial No. 310,674.

of the residual alkali to the required extent, besides conserving raw materials.

Paper or board from pulp treated by this process possesses a more open structure than paper made under my process patent application Serial No. 228,104, filed October 22, 1917, now become Patent No. 1,761,109 granted June 3, 1930. Moreover the color of the paper is lighter than the paper made by the above process when an iron salt is used. The product has'less tendency to soften with age than that produced by the processes heretofore used.

I claim:

1. The process of making pulp or paper from. unwashed or partially washed pulp which has been digested by an alkaline process which consists of adding chlorine to such pulp to stabilize or fix organic compounds 7 contained therein.

2. The process of treating partially washed or unwashed pulp which has been digested by an alkaline process which consists in subsequently adding chlorine to such pulp to stabilize or fix'organic compounds contained 5 therein and afterward making paper or paper board from the pulp so treated.

The process of treating partially washed or unwas 1 by an alkaline process which consists in subsequently adding chlorine and water to such pulp to stabilize or fix organic compounds contained therein and afterward making paper or paper board from the pulp so treated.

LEVIS MILLER- BOOTH.

ed pulp which has been digested p 

